A path to migration
Legacy systems won’t last forever; planning upfront is key
By Marjorie Ochsner and Walter Guy Wiles III
Like most others in the region, the DuPont DeLisle Titanium Dioxide plant sustained heavy water and wind damage during Hurricane Katrina. As was the case with other plants, a large share of the DuPont’s facility’s process automation and control room equipment suffered severe damage.
One saving grace that quickly helped the plant get back on line was DuPont had implemented a comprehensive lifecycle management strategy for the plant’s process control and safety systems. They underwent a detailed analysis of the plant’s existing system and put a multi-year plan in place. This system encompassed 20,000 I/O points.
For manufacturers, improving the performance and business results of Brownfield plants, whether they suffered through a natural catastrophe or not, through control system migration has become an important strategic initiative. The typical drivers for migration projects include the impact of downtime of existing control platforms, the cost of maintaining obsolete equipment, and the need to acquire or supervise global business data.
The need to upgrade to newer automation capabilities means industrial operations must select the best migration strategy and technology solutions based on things like control reliability, data configurability, network architecture support, plant standardization, and safety-instrumented systems (SIS) integration.
Over the years, consolidation of automation vendors has created some confusion for manufacturers, especially when it came time to upgrade their process control systems. Let’s face it, in the aftermath of vendors integrating, some legacy systems were outright abandoned by their new owners. For process plants, the critical issue in control system migration is deciding when to jettison the old in favor of the new. However, obsolescence does not happen on a specific date, but rather is a gradual process that starts when a vendor discontinues support. Spare parts become more difficult and more expensive to procure.
In most companies, quite a few projects vie for the same capital dollars. When migration projects do get funding approval, it is imperative they are successful to gain justification for other automation projects.
The first task in any migration project is determining the process for selecting the future control system. The process used for this selection often determines customer satisfaction with the new automation solution. Faced with increasing performance demands, industrial facilities need a seamless platform that provides the foundation for integrating process control and safety systems, along with automation software, under a single, unified architecture. They also require software applications that enable the capture and sharing of process knowledge. Additionally, plants seek collaborative decision-support tools that help minimize disruptions and overcome abnormal situations.
With an open, tightly integrated automation solution, end users can unify plant safety and control, providing increased safety, security, and system dependability. They also gain a single facility-wide view of operations, plus the interfaces with industry-standard digital network protocols to optimize existing assets.
End users will also be able to integrate mobile computing capabilities through the adoption of wireless solutions that extend the reach of automation. New wireless field data collection systems enhance asset management by integrating field data with data from other sources, including production, process control, and work management systems.
HMI migration is one of the most important aspects of control system modernization.
When it does come to a migration, operator acceptance is a key intangible that can determine migration project success. Because the control system is a direct operator interaction device, even if the new technology outperforms the legacy system, a lack of consideration for operator needs can lead to failure.
The human machine interface (HMI) included in distributed control systems (DCS) is most vulnerable to support issues. At quite a few plants, multiple types of HMIs are in play. At some point, the HMI hardware will exceed its life expectancy or the cost of finding replacement parts will become prohibitive.
End users need a solution that allows the new HMI to communicate with existing controllers on a continuous basis. Ideally, the new HMI would run in parallel with the current one for some period, giving operators a feeling of continuity during the transition.
Communication and interfaces with third-party devices can be a major stumbling block to automation system upgrades. Control systems frequently communicate with legacy systems, such as programmable logic controllers, safety systems, and advanced applications. Identifying these systems and determining a detailed interface plan is essential for an effective migration.
When it comes to a control system migration plan, best practices can reduce or eliminate risks. First and foremost, consider the scheduling of any migration. Long-term planning for multiple migration stages will help to ensure maximum return on investment (ROI) and minimal disruption.
System cutover requires careful planning to minimize risk. A comprehensive cutover plan is a critical requirement for seamless transition to a new control platform. Without proper preparation, migration projects can feel the affect of cutover delays and other unexpected issues that may cause downtime.
Industrial operations need an easy, low-risk transition path to modern control system architecture. With an effective migration solution, companies can continue using existing technology while building for the latest digital technologies.
Unifying process variables, business requirements, and asset management allows end users to transform process control beyond traditional DCS functionality. An automation system needs to focus on plant personnel and make the most of their knowledge.
With integration of new and legacy systems, controller data has the same look and feel, regardless of where the data originates. Operator effectiveness improves by merging multiple platforms. Plant personnel have seamless access to points, alarms, operator messages, and history between servers. Moreover, they can access a single virtual database without duplicate configuration.
The integrated control infrastructure can automatically detect alarms and events and operators have system-wide acknowledgement. You can achieve secure control access by using OLE for Process Control with vendor-specific extensions. A truly unified system solution allows peer-to-peer communication between legacy systems and the application control environment. It also provides a common security model, as well as fault tolerant communications with full redundancy.
Effective control system migration does not end with a single modernization project. Industrial plants need a cost-effective approach for maintaining up-to-date process automation functionality and minimizing risks associated with system upgrades.
Continuous control technology evolution is the goal of lifecycle management. Users can accomplish this by establishing a committed automation roadmap that leads to either electronic refresh or complete migration. Lifecycle support allows plants to start modernizing and progress incrementally as needs and schedules dictate.
A lifecycle management solution should offer flexibility in how companies manage their plant assets and predictability in how their choices are financed, including the freedom to choose when to modernize, how to fund the transition, and how long to maintain current capabilities. In this way, companies can effectively extend equipment life while providing a secure path forward to the latest advanced control technology and functionality.
End users should partner with a company offering multiyear agreements that guarantee parts availability and support until a modernization occurs according to site operating plans. Such agreements provide:
Locked-in pricing on spare parts, support contracts and migration/upgrade kits
Reduced risk and increased reliability via guaranteed maintenance
Long-term protection from equipment obsolescence
DuPont gets back on track
Going back to the DeLisle Titanium Dioxide plant, after the floodwaters subsided and folks were able to get back in, DuPont kicked off an ambitious rebuild of entire process control system. Plant management viewed the DCS recovery as an opportunity to replace outdated equipment. Due to migration planning completed prior to the hurricane, DuPont quickly identified the path forward. For example, the project accelerated migration from its legacy system to upgrade to more powerful controllers. They also updated UPS, grounding, and power distribution systems. Most panel-mounted instruments also received a technology refresh.
As a result of the DCS recovery effort, DuPont was able to restore the DeLisle operation to commercial production ahead of schedule. This project highlighted why everyone should have an emergency preparedness and recovery plan. It also proved the value of technology migration.
Properly planned and implemented, a control system migration enables end users to migrate legacy control platforms at their own pace, allowing new controllers to come on line at any time and integrate them with existing controllers. It also permits migration of subsystems and function blocks to new controllers whenever the user decides.
For a successful migration project, end users must take control of their existing system and clearly define upgrade goals and objectives. Then they must determine the optimal migration strategy. A structured, organized approach to system migration enhances the benefits of technology upgrades and preserves the intellectual property contained in legacy systems. Regardless of vendor support, end users should play an integral part in the migration effort, reviewing its progress every step of the way.
Plan, plan, plan
As part of good engineering and project management practices, plants should take the following steps during migration planning:
Determine the best time to migrate.
Determine the best migration path.
Define the project through front-end engineering.
Use a proven approach with comprehensive checklists.
Develop detailed cutover plans.
Define intermediate operability and training plans.
As with any large, complex project, planning for control system migration is the key to success. The most important parts of a migration plan are the process definition and functional specification documents, defined at the start of the work. If you do not wrap up the detailed planning prior to beginning the project, everything takes longer and can end up costing more.
To ensure a successful technology migration, end users should plan for the change, identify a critical timeline, conduct regular (perhaps daily) meetings, communicate with those affected by the change, identify all available resources, and plan for contingency resources.
A formal migration plan identifies strategies for existing control system nodes, such as controllers, HMIs, and supervisory computing nodes. It also includes proposals for consolidating existing control systems in order to reduce costs and enhance safety. Additionally, the plan provides recommendations for ensuring the reliability, robustness, security, expandability, and ease of diagnosis of process control networks.
One obvious need during the planning process is a system assessment, which is essential for determining currently installed assets, as well as identifying current maintenance costs. The assessment outlines areas for improvement, the anticipated value of those activities, and specifies actions that will achieve improvements.
The system assessment typically includes:
Audit of the current system and process
Recommendations for HMI migration and effective operator displays
Recommendations for base regulatory and advanced control improvements
Strategies for migrating hardware and software and protecting current installation investments
Plans for personnel training and implementation
Recommendations for optimization and integration
Migration projects can be more complex than they appear at first glance. There are other issues such as space allocation, HVAC, and power considerations. They can have significant impact when not identified early in the project. Upfront engineering defines the detailed migration work scope and estimates the overall cost of upgrades. Front End Loading (FEL) can identify potential difficulties with a migration project and provide plans to mitigate risks. An FEL study analyzes all aspects of the project, including mechanical, civil/structural, instrument, electrical, and controls. The result of FEL is an overall design specification, outlining the strategy and schedule for migration activities.
Industrial facilities need to choose the migration methodology best suited to their specific needs. Typical migration options include:
Phased migration: Allows system modernization in gradual steps, replacing the HMI or a particular unit first. Once completed, the end user can replace the rest of the system over several years.
Complete replacement: Allows the user to rip out the entire system all at once during a planned outage. In some cases, hot cutover can minimize system downtime and ensure seamless integration of current control assets.
System upgrade: Allows an upgrade of critical system components at the end user’s pace. The main automation contractor must retain the value of existing systems and continue to offer parts and support for the legacy platform.
HMI migration is one of the most important aspects of control system modernization. Upgrading legacy DCS operator stations to the latest HMI technology allows plants to provide a common user interface to the integrated control architecture, reducing training and maintenance requirements by keeping existing graphics, networks, controllers, and I/O in place. It also provides direct access to the control network with read/write data access and integrated alarms and events.
Frequently, when a control system requires change, replacing existing controllers also makes economic sense. For migration, there needs to be two key functions: You must be able to easily and quickly move the existing field signals to the new control system, and you need to migrate, and improve, the existing control schemes.
For a large-scale retrofit, it is often best to use a phased approach. Phased migration eliminates risk by incrementally narrowing the focus, while providing a fallback position to the old system. This approach requires communication with the existing system for interim phase-in, physical coexistence with the old equipment to enable a hot cutover, and the ability to switch quickly and easily between old and new signals for testing/tuning purposes.
Phased migration does have its drawbacks in terms of cost and time, but it is a lower risk approach with less downtime. Further risk and downtime reduction can occur by simulating the new system prior to installation.
Gaining an edge
A well-executed migration plan provides significant operational and business benefits through seamless integration of new and existing automation systems. By incorporating existing data, events, and operator messages into the control architecture, and providing a common operator interface, the legacy system appears as an extension of the new system.
From managing existing parts or infrastructure to upgrading hardware and software, an effective migration solution can maximize the end user’s ROI while helping them maintain predictable year-over-year expenditures.
The specific benefits of control system migration include:
Increased protection of asset investments
Reduced modernization risk
Increased plant reliability
Improved process performance
Improved operator effectiveness
Fewer unscheduled shutdowns
Greater productivity through a faster network
Enhanced platform for advanced applications
Improved human interface functionality
Reduced engineering time
Improved ease of communication with third-party systems, devices and software
Increased wiring and I/O savings
Reduced service and implementation costs
Lower component costs as compared to legacy systems
In this age when manufacturers need to hike productivity, control system migration projects have the potential to deliver great value to industrial plants. The process used to arrive at migration timing and scope has considerable influence on that outcome. The most critical consideration is planning. The more upfront detailed planning performed, the lower the risks in the execution phase of a project.
ABOUT THE AUTHORS
Marjorie Ochsner (Marjorie.Ochsner@honeywell.com) is a senior product manager for system migrations, Honeywell Process Solutions. Walter Guy Wiles III (W-Guy.Wiles-III@USA.dupont.com) is an electrical engineer for DuPont in the DuPont Titanium Technologies SBU.
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